Wave guide discharge tube socket assembly



June 22, 1948. J. M. LAFFERTY WAVE GUIDE-DISCHARGE TUBE SOCKET ASSEMBLY Original Filed Feb. 25, 1943 3 Sheeis-Sheet 1 Inventor. dames MLafferty, by @a/117 /Mf l His Attorney June 22, 19548. J. M. LAFFERTY 2,443,917

WAVE GUIDE-DISCHARGE TUBE SOCKET ASSEMBLY Original Filed Feb. 25,` 1943 5 Sheets-Sheet 2 TSS. 2.

7 8 8 lo ll iglo. 6*

| /5 l 5 I nfPELLmG l ELEcTRoDE I nF`i' .I I. l 2

'200 -/AEARD/NG AND A FOCUS/NG ELECTRODE fg D 0 h zoo 4 7 E ""5 400 soo 60o t '00 o/APHRAGM |200 @@7 Inventor; 40 James M. Lafferty, 38 by 7%@ )MVM His Attorney.

June 22, 1948. J. M. LAFFERTY WAVE GUIDE-DISCHARGE TUBE SOCKET ASSEMBLY 5 Sheets-Sheet 3 Original Filed Feb. 25, 1943 Inventor James MLafFert H i5 Attorney Patented June 22, 1948 WAVE GUIDE DISCHARGE TUBE SOCKET ASSEMBLY James M. Lailerty, Schenectady, N. Y., assignor to General Electric Company,

New York Original application February 25,

477,065. Divided an 1945, SerialNo.

4 Claims.

My present invention is a division of my application S. N. 477,065, filed February 25, 1943, now Patent No. 2,421.273, and relates to high frequency electric discharge devices and systems and more particularly to ultra high frequency electric discharge devices of the space resonant type employing velocity modulation principles.

It is an object of my invention to provide a new and Vimproved construction for an ultra high frequency electric discharge device wherein connection to the ultra high frequency circuit and manipulation of the device as a whole is facilitated.

In accordance with my invention, there is provided a new and improved construction for an ultra high frequency electric discharge device wherein connectionto the ultra high frequency parts ou' elements of the device may readily be made and wherein the arrangement of the elements and the supporting and enclosing structures are cA mpact and susceptible of ready manipulation for xse in ultra high frequency systems.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims. Figs. 1 and 2 are cross-sectional longitudinal views of an electric discharge device of the velocity modulation type built in accordance with my invention, and Figs. 3-6, inclusive. are detailed cross-sectional views of this discharge device. Figs. 7 and 8 illustrate the high frequency concentric transmission ine construction employed and also illustrate steps in the method employed for forming the transmission line assembly into the desired configuration for use in the device shown in Fig. 1. Fig. 9 shows in cross-sectional view a socket arrangement for receiving the discharge device base terminals or prongs for adaptation to an ultra high frequency system such as a dielectric wave guide. Fig. 10 is an enlarged diagrammatic sketch showing a possible distribution of equipotential lines of force in the retarding and reversing regions of the discharge device, and which also illustrates the paths of electrons having different amounts of energy and the probable paths of such electrons. Fig. 11 shows the manner of variation of the radio frequency or the ultra high frequency modulating voltage which appears across the modulating gap within the space resonant cavity.

Referring now to Fig. 1, my invention is there illustrated as applied to an ultra high frequency electric discharge device comprising an enclosing envelope I, preferably of rigid construction, comprising a metal such as iron, and which dea corporation of 1943, Serial No.

d this application July 26, 607,113

nes at least in part an evacuated space within which are positioned the various elements or electrodes of the discharge device described hereinafter. The envelope I is supported by and sealed to a base 'member 2 which comprises a flanged 'metallic part 3 provided with an annular trough in which the lower end of envelope I is seated and which contains a suitable sealing means such as a solder 4. A plurality of prongs or terminal posts 5-I 2, inclusive, are supported by an insulating part I3 of base member 2 in insulated relation and which serve as externally accessible contacts for the electrodes of the discharge device. Only six of the aforementioned terminal posts are visible in the views shown in Figs. 1 and 2.

An orientation protuberance for guiding the insertion of the base member 2 and the terminal posts into an associated socket is provided and is preferably centrally located. The orientation protuberance may comprise a tubular extension I4 of insulating material formed integral with part I3 and having a central opening through which extends a concentric transmission line comprising an inner conductor I5 and an outer tubular conductor I6, which is sealed to the top surface of part 3. The transmission line just described is terminated near its upper end by means of a sealing insulator II within conductor I6 aud which not only serves as mechanical support and positioning means for the inner conductor I5, but yalso serves as the means for sealing these elements to maintain the desired degree of evacuation within the envelope of the discharge device.

Within the envelope I and preferably centrally located near the lower part of the defined space, I provide a thermionic cathode which may be of the indirectly heated type comprising a metallic cylinder I8, preferably coated on the exterior of the upper closed end with an electron emlssive material, such as an alkaline earth metal, to serve as a source of electrons. A cathode heating element I9 is centrally positioned within the cylinder I8 and is supplied with energizing current through a pair of conductors 20 and 2|, the former of which is shown in Fig. 2. Conductor 2| is connected to terminal post II. Conductor 20, shown in Fig. 2, may be of suflicient rigidity to position firmly and hold the cathode assembly in the position illustrated, being supported from an insulated part of the anode structure assembly to be described presently. The cathode structure may comprise at its lower extremity a metallic ring 22 supported by conductor 20 and which serves as a support for the cathode cylinder I8, to which it is attached by means of a plurality of circumfermay comprise a disk-shaped metallic part 2B and is preferably constructed of copper supported in the illustrated horizontal position by means of a ring 28 of solder adapted to engage appropriately formed shoulders on the periphery of disk 25. At the central part of the disk 2B there is provided a central opening defining a space resonant region or cavity 21. The details of the anode structure are shown in Figs. and 6, the former of which is a plan view and the latter of which is an enlarged cross-sectional view. The disk 25 is provided with' a plurality of annularly spaced apertures 2044, inclusive, which are employed and adapted to receive assembly bolts or to permit the passage therethrough of conductors described hereinafter. 'I'he disk 25 is provided with a recess '35 which is in communication with the space resonant cavity 21 through a radial opening 3S preferably of cir'- cular cross section, and which houses one end of a concentric transmission line shown in Figs. 1 and 2 and illustrated in detail in Figs. '7 and 8.

As a means for defining one boundary of the space resonant cavity 21 and also for providing an entrance and directing structure for the electron beam, I provide an entrance part 31 preferably constructed of metal, such as copper, and which is adapted to be seated in a recess in the bottom face of disk 2,5. The entrance part I1 comprises a conical member 3l having a tapered aperture l! through which the electron beam passes and which defines with one boundary of the space resonant cavity 21 a velocity modulating gap 40 for the electrons constituting the beam.

l In order to control the natural frequency by controlling the physical dimensions of the space resonant cavity 21, I provide a deformable member, such as a flexible metallic diaphragm 4I, which constitutes one boundary or the cavity and which is provided with a central aperture 42 to ailord a communicating path between the cavity and the electron retarding and reversing regions described hereinafter. Diaphragm 4I is seated upon the upper surface o1' disk 2l or may be seated upon a metallic spacer 43. Disk 25 is also provided with apertures 44 which are adapted to receive and hold in insulated relationship conductors for supporting gettering means.

Returning now to Fig. l. I provide control electrode means for establishing electron repelling and retarding electric ilelds and which may take the form of a pair of disks 46 and 41 lwhich are insulated from each other and from the anode structure comprising disk 25.by means of annular dielectric washers 48 and 49, the latter disk being provided with a central aperture 50 to permit the e of electrons therethrough into the region dened between disks 48 and 41.

In order to impress suitable potentials on the disks 4l. and 41, I provide a pair of conductors Il and 2, shown in Fig. 2, which extend through apertures II and 28 of anode disk 25 and are positinned or terminated in apertures provided by the first mentioned disks. Conductor l5I extends through disk 41, but not in electrical engagement therewith, and is terminated in disk 46, while conductor l2 is terminated in disk 41. This detail of construction is illustrated in Fig. 2 wherein conductors 5I and 52 are shown connected to lead-in Wires 5l and 54 which are connected to terminal posts l and I0, respectively.

To focus the electrons emitted at the end of cathode cylinder Il, I provide a focusing electrode means which may comprise a ilanged cylinder 55 shown in Fig. l, the flanged part which serves as the supporting portion being electrically insulated from the anode disk 2i by means of an insulating spacer ll. A suitable negative focusing potential may be impressed on cylinder Il by means of a conductor l1 which is seated in an aperture of the flanged part of the cylinder and which is connected to terminal post I2 through lead-in wire Il. In order to derive ultra high frequency energy from cavity 21, I provide a curved ultra high frequency concentric transmission line which extends from the cavity 21 to the base member 2 to facilitate external connection to the device. The concentric transmission line comprises an inner conductor Il, an outer tubular conductor 60 separated by a pulverized insulator, such as a vitreous material il which ma!1 be quartz. 'I'he inner conductor Il extends into the cavity 21 and serves as an output electrode means and may take the form of a loop l2, 'whereby the transmission line is coupled to the cavity. The details of the transmission line and the method of forming it will be considered in detail in connection with the discussion relative to Pigs. 'I

and 8.

At the lower extremity of the transmission line comprising conductors 6I and tl, I provide an adaptor assembly shown in detail in Fig, 8 and which comprises a recessed metallic cylinder u supported at the lower end of the outer conductor 60. Within the recess of cylinder Il there is provided an adaptor for the inner conductor Il which comprises a metallic cup-shaped part 04, in turn being provided with a recess il which engages the upper end of the inner conductor Il of the transmission line supported within the orientation protuberance I4 of the discharge device. The outside diameter of cylinder Il is chosen so that the adaptor assembly snugly fits the inner surface of conductor Il.

To assure a good electrical contact between cylinder i3 and conductor II and between conductor IB and part $4, respectively, the outer surfaces of cylinderl 63 and part Il are tinned prior to the assembly operation. lAfter assembly of the elements in the positions shown in Fig. 1, upon the application of heat thereto, the tin forms a firm contact between the elements, that is between cylinder I3 and the inner surface of conductor I6 and between conductor Ii and part i4, respectively.

As a means for mechanically controlling the form and position of the diaphragm 4I, I provide externally accessible actuating means for exerting difIerent amounts of pressure thereon, thereby controlling the dimensions of the space resonant cavity 21. This means may comprise an assembly supported by the flat top of the envelope I and may include an actuating rod constituting a vertically adjustable or positionable member of the actuating means. Rod Il is connected to the diaphragm 4I by a pair of rigid wires B1 and 0l which are welded to rod Il. Alternatively. instead of wires l1 and Il being welded to the diaphragm 4I, these rods may be seated in an annular groove provided in the diaphragm and the diaphragm formed to have a re.

siliency tending to restore the diaphragm to an upward or vertical position whereupon the diaphragm is maintained in contact with rods 61 and 98. In such instance, the control of the form of the diaphragm will be accomplished by the amount of downward vertical pressure exerted thereagainst. Within the enclosure provided by envelope I and supported by the inner surface of the envelope, I provide a sealing structure of deformable character which may comprise a.

metallic bellows 68 which is welded or soldered to the inner surface of envelope I and which is welded or soldered to ametallic cup which in turn is sealed to the outer surface of 'rod 66.

Above the envelope I and in an externally accessible position, I provide a vernier adjustment 1I for the actuating rod 86 where, upon actuation, the rod 66 is moved to position the diaphragmrlI in minutely determinable degrees to obtain a desired control in the operating frequency of the device. 'I'he actuating rod 66 may be hollow, having an opening 12 extending longitudinally, thereby providing an evacuation channel or tubulation for the discharge device which after evacuation may be sealed at its top.

To maintain the elements including the anode disk 25, the repelling electrode 46. the focusing electrode I1, the focusing cylinder 55 and the interspaced insulating Washers in the desired assembled spaced relationship, I employ suitable mechanical engaging means which may comprise a plurality of bolt and nut assemblies 13-16, inelusive, which are shown in the plan view in Fig. 3. Also shown in that ligure are a plurality of gettering means which may include a Vaporizable material supported by metallic strips and which is flashed during the evacuation process in order to absorb occluded gases. For example, I may employ getters carried by metallic strips 11, 18 and 19 which are supported by a plurality of vertical conductors 8D, 8| and 82 shown in Fig. 4 and which are connected to three terminal posts supported by base member 2. The conductors III-82, inclusive, extend through the anode disk 25 and are insulated therefrom by suitable glass insulators such as glass-to-metal seals 83, 84 and l5, a longitudinal view of seal 85 being shown in Fig. l.

Fig. 4 is a cross-sectional view of the discharge device shown in Fig. 1 and represents the arf rangement of some of the conductors, particularly the connections to the cathode. In this view there is shown conductor 86 which serves as the other lead-in conductor for the cathode heating element I9; this conductor is attached to the same metallic part of the anode structure as conductor 20 (Fig, 2) and thus completes a circuit to element I9. Conductors 20 and 86 serve as a cathode connection.

The method of making and forming the concentric transmission line comprising conductors 58 and 80 to assume the curved conguration' shown in Fig. 8, without establishing excessively high voltage gradients between the conductors at the points of curvature and to minimize reections, may be more readily appreciated by referring to Figs. 'I and 8. The concentric transmission line is initially constructed using straight conductors, and an insulating body in solid form, such as a vitreous or quartz tube, is placed between conductors 59 and 60. The vitreous tube insulator 81 may be manipulated in the manufacturing process in a number of ways. For example, the vitreous tube may be fused to the inner conductor 59 and formed to have a diameter to permit insertion within the outer tubular conductor III. Alternatively, the inner conductor 55 may be inserted in a longitudinal opening in the quartz tube 81 and the assembly inserted within the outer conductor GII.

To assure the uniform distribution of the dI- electric, that is the insulating material afforded by tube 81, the concentric transmission line assembly shown in Fig. 7 is swaged to effect thorough pulverization of the quartz tube so that it constitutes after the swaging operation finely divided particles readily susceptible of assuming an ,even distribution within the outer conductor GII. The next step comprises the deformation or bending of the transmimion line assembly into the configuration desired. Where it is desired to -obtain a U-shaped configuration, such as that shown in Fig. 8, for adaptation in the discharge device shown in Fig. 1, pressure may be exerted in succession or simultaneously at appropriate positions to bend the line assembly. By virtue of the fact that the quartz is now in a pulverized state, upon bending of conductors 59 and 60 the particles assume an even and uniform distribution at the points of curvature, thereby aifording adequate insulation at all points and effecting minimization of reflections and high voltage gradients at these positions.

Electric discharge devices built in accordance with my invention are susceptible of great freedem and ilexibility of application to ultra high frequency systems. By virtue of the concentric transmission line outlet within the orientation protuberance I4, and because of the compact arrangement of this -protuberance with respect to the terminal posts, the electric discharge device as a whole may be readily positioned in an appropriately designed socket to effect simultaneous connection to the terminal posts and to the concentric transmission line outlet.

Fig. 9 illustrates one arrangement for connecting an electric discharge device of the type shown in Figs. l and 2 to an ultra high frequency transmission system which comprises a dielectric wave guide 88 of the hollow pipe type defined by a plurality of conductive or metallic members through which electromagnetic waves may be propagated. A terminal box 89 may be seated directly on the top surface of th'e wave guide and is provided with a tubular inlet channel 90 for conductors which are to be connected to prongs 9I of a socket 92 adapted to receive the base and terminal posts of base member 2 of the discharge device shown in Fig 1. Within the terminal box 89 there is provided a contact assembly 93 adapted to make electrical contact with the concentric transmission line comprising conductors I5 and I6. The assembly comprises a tubular member 94 provided with a flanged part 95 which is seated on the upper surface of the bottom plate of the terminal box and which is provided near its top with a plurality of annularly spaced resilient contact fingers 96 adapted to receive the lower portion of the outer conductor I6 and to maintain firm electrical contact therewith. An inner conductor 91 is adapted to contact inner conductor I5, thereby completing the connection of the high frequency concentric line in the orientation protuberance I4 to the transmission line constituting the tubular member 94 and conductor 91. Conductor 91 at its uppermost part may be hollow providing an opening, the inside diameter of which is sufficient to permit the insertion of the inner conductor I5 therein and to engage closely amaai? th'e latter to establish electrical connection to the ultra high frequency system. s

Conductor 81. may be maintained in the desired central position by means of an annular insulator 98. A'portion of the conductor Il serves as excitation means or electrode means for establishing the energization of the wave guide' and may take the form illustrated in Fig. 9 where it extends completely through the guide and is terminated in a tuning plunger assembly ll comprising an outer tubular conductor and a vertically positlonable plunger Ill having a plurality of resilient fingers to engage the inner surface of conductor llt. Vertical movement of plunger III may be effected by means of an adjusting means ill! which is connected to plunger lill through a hollow cylinder |03. Additional tuning means comprising a plunger IM may also be associated with the waveguide and this plunger in turn may be operated by the adjusting means |05.

The operation of the embodiment of my invention described above will be considered with particular reference to Figs. 1 and 2 and the schematic arrangement of certain of the electrode elements shown in Fig. 10, when the device is operated as an oscillator. Generally speaking, the electric discharge device is of the velocity modulation type wherein the electron beam is velocity modulated periodically so that successive groups of electrons are alternately accelerated and decelerated, tending to group the electrons in the beam after the beam has traversed the velocity modulation gap. 'I'he particular form of electric discharge device described above operates in accordance with reflex principles. After undergoing velocity modulation, the electrons are given an opportunity to assume a charge density distribution incident to the effect of the velocity modulation and are reversed in the direction of travel to re-enter the space resonant cavity, delivering energy to the electro-magnetic field thereof or to an associated electrode construction. In the device described above, an electron beam is established by virtue of a unidirectional potential impressed across the anode structure comprising disk and the cathode cylinder il. The electrons of the electron beam initially assume a velocity determined by the accelerating potential impressed on the anode structure and the electrode geometry. A negative potential with respect to cathode cylinder I8 is impressed on the focusing cylinder 55 which tends to restrict the. size of the electron beam, confining it to a. relatively small transverse area in order that a large percentage of .the electrons pass through the space resonant cavity 21 through the conical part 38. Assuming an excitation of the cavity 2l by virtue of sporadic motion of the electrons therethrough during the starting operation, cavity 2l will be set in oscillation and there will be established across the modulating gap 40 an alterhating ultra high frequency potential incident to the electromagnetic field within the cavity 21. By virtue of the alternating nature of this potential, electrons whichare in the effective region of gap 40 during periods of time when .the diaphragm 4i is positive with respect to the conical part 38 will undergo an acceleration. During the following half cycle, that is the negative half cycle when diaphragm 4l is negative in potential with respect to conical .part 38, the electrons will undergo a deceleration. The curve A in Fig. 11 represents the radio frequency voltage appearing -across the modulating gap 40. Consequently, the electrons after traversing the space resonant cavenergy of an electron may be referred to a voltage which will accelerate the electron to a particular velocity establishing that amount of `kinetic energy, and consequently the kinetic energy of the electrons may be referred to a retarding field which visjust suillcient to stop the motion of the electrons. The faster electrons obviously travel farther in this field, before they are stopped or reversed, than the slower electrons.

The probable paths of electrons within the fields produced by retarding electrode 41 and repelling electrode I6 are represented by curves a, b and c in Fig. 10. The equipotential lines shown in Fig. 10 were obtained from tests conducted on an enlarged electrode construction employing an elcctrolytic solution and probe for determining the equipotential lines, and for the condition where a 1600 volt difference was present betweenthe anode structure and the cathode and where the repelling electrode I6 and the retarding electrode 4l were maintained at negative 500 and volts, respectively. The field distribution is plotted showing only one-half the region, and it is to be understood that the other half region ls similar in connguration to that illustrated. The curved lines extending from diaphragm 4| to the conical part I8 represent the contou-r of the electric lines of force present in the cavity during one-half cycle that is the positive half cycle, during whichthe electrons are accelerated. The circled crosses represent the corresponding direction of the magnetic componentv of electromagnetic field during the same half cycle. During a half cycle of opposite polarity the electric component and the magnetic component, of course, are reversed in direction. The curve a represents a low velocity electron which traverses a distance corresponding to the 200 volt equipotential line and is reversed in its direction of travel and focused so that it re-enters the cavity 2l. An electron of greater kinetic energy corresponding in its path to curve b travels a greater distance before reversal and as illustrated is reversed within the vicinity of the zero potential line. Lastly, an electron of even greater velocity proceeds in the direction of the repelling electrode 46 and enters the negative field prod-uced thereby, undergoing a reversal in the vicinity of the negative 200 volt line.

One way in which the electric discharge device described above may -be operated is by impressing a negative potential on the retarding electrode 41 and a stili greater negative potential on the repelllng electrode 46. For example, a negative unidirectional voltage of 300 volts may be impressed on the retarding electrode l1 and a negative unidirectional potential of 500 volts may be impressed on the repelling electrode 46, the anode structure being maintained at a positive potential of 1000 volts. The focusing cylinder `55 may be maintained at a negative potential of 100 volts. It is to be understood that the above values of voltage are merely representative of voltages which may be applied in the operation of my device and are in no way critical or limiting.

Electrodes 46 and 41 serve two purposes. One is to impress on the electron beam proper radial voltage gradients, and the other is to control the grouped electrons incident to the velocity modulation effect so that these electrons return and pass through gap 4I in the proper phase relationship with respect to the electric component of Ithe electromagnetic field within cavity 21.

The electric discharge device may be operated in a number of ways in addition to that described above. One example oi' an alternative manner of operation is by impressing on the repelling electrode 46 a potential electrically near the cathode potential and the electrode 41 at a positive potential with respect to the cathode. In this manner oi' operation, all electrons which gain velocity passing through the velocity modulation gap 40 are collected .by electrode 46. The electrons which lose velocity due lto the decelerating effect i of the gap are reflected. Consequently, the returned electron beam is conduction-current modulated.

In accordance with one aspect of my invention, I have found that highly satisfactory operation of the device and minimization of losses may be obtained by maintaining a relatively large ratio between the unidirectional accelerating voltage and the high frequency component of voltage. The change in velocity, under these conditions, in comparison with the initial velocity of the electrons in the beam is small. Consequently,

-practically equal numbers of electrons approach and leave the gap. and the currents induced in the cavity by approaching electrons are offset by currents of opposite sign induced by currents of the departing electrons.

Where the discharge device is operated by impressing progressively negative potentials on electrodes 41 and 46, I have found that optimum operation is obtained when the ileld incident to these electrodes is such that the zero potential line lies within the vicini-ty of electrode 41, causing -the electrons to travel a. minimum distance before reversal but not sacricing the utilization of the proper phase relationship between the returned electrons and the electromagnetic fleld in order to obtain large power outputs.

Considering 4the transit time of the electrons within the space resonant cavity 21 and in the field produced by the repelling electrode 46 and retarding electrode 41, it may be generally stated that the transit time or the time-phase relationship of the electrons is such that there is a net positive energy transfer from the electrons to the lfield of the cavity. The velocity modulated electrons, after undergoing reversal within the field produced by electrodes 46 and 41, because of the grouping of the electrons by vir-tue of the velocity modulation. assume a charge-density distribution. The velocity modulation effect has such a timephase relation with respect to the charge-density variations of the beam, that the electnons within the regions of large charge density are slowed down, and those of small charge density are accelerated. Thus, there is a net yreduction in the average speed of the electron beam which is just sufficient to supply the external power derived from the cavity by loop 62 and the power dissipated as a loss in the cavity.

The transit time in order to effect optimum transfer of energy from the electron beam to the ileld cavity may be generally stated as being (n+%) cycles, where n is zero or any positive integer, and where the transit time is measured in the path of an electron during its excursion from the diaphragm 4i outward into the ileid space of the retarding and repelling electrodes and returned across the gap 4l to the uppermost plane of conical part ll. In order to obtain the most effective utilization of space and to obtain a discharge device of .small proportions, it is important that the distance traveled by the electrons after velocity modulation to acquire the desired charge density modulation be minimized. Consequently, I have found that it is desirable to utilize a zero value or a small value of n so that the electrons assume the desired charge-density modulation distribution without entailing the passage through a great longitudinal distance either in the forward direction oi travel or in the reverse direction of travel. 0f course, to utilize space most effectively in a discharge device of this nature, the high frequency modulating voltage appearing across the modulating gap 4l should be maintained at an appreciable value to impart to the electrons the desired velocity modulation characteristic within the distance or space under consideration. By employing an appreciable value of modulating voltage in combination with a relatively small transit time, such as 3/4 or "/4 cycles referred to the cavity excitation, I provide an eillcient arrangement for exciting the cavity without involving the use of long electron paths, and which permits the construction of discharge devices of smaller dimensions than that afforded by the prior art constructions or methods of operation.

In the operation of devices built in accordance with my invention and employing the above described structure, I have found that the electron beam to some extent is focused by the positive ions from gas molecules produced by the impact of the electron beam upon them. Thus, positive ions then neutralize the negative charge of the electrons of the beam and thereby prevent the mutual repulsion of the electrons to limit the beam spreading. This effect occurs at pressures greater than 10-6 mm. oi' mercury. That such a gas focusing action occurs is readily apparent by an examination of a device after operation by observance of the discoloration or marking at the center of the cathode emitting surface and the repelling electrode 46, As the pressure is reduced, of course fewer ions are focused and the same field which accelerates the electrons also removes the ions formed, thereby reducing the amount of focusing due to the positive ions.

'I'he operating frequency of the electric discharge device may be controlled either by controlling the physical dimensions of the space resonant cavity 21 or by controlling the voltage impressed on the electrodes including the voltage on the anode structure and the voltage on electrodes 46 and 41. Considering first the control of the operating frequency by virtue of the change in the physical dimensions of the cavity, the position of diaphragm 4I controls one boundary of the cavity and consequently controls its natural frequency. Ready adjustment of the position of the diaphragm 4i is obtained by manipulation of the Vernier 1i. I have found that in electric discharge devices built in accordance with the above described principles and construction, the operating frequency of the discharge device may be varied throughout a range of 6000 megacycles and that the discharge device has an effective and substantial power output Vwhen operating at 30,000 megacycles.

impressed on the repelling electrode 46 and thek retarding electrode 41, in this manner controlling the transit time of the electrons in the beam and consequently controlling the phase of charge maxima or charge minima of the charge-density modulated electrons which are returned to the space resonant cavity 21 with respect to the field thereof. By using this method of controlling the operating frequency, I have found that an additional finer adjustment of range of 90 megacycles frequency control may be obtained.

I have found that the above described con-. struction of an ultra high frequency electric discharge device is peculiarly adaptable for the production of discharge devices of exceedingly small size.

While I have shown and described my invention as applied to an electric discharge device employing electrodes of particular configuration, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I, therefore, aim in the appended claims to cover all suchvchanges'and modifications as fallfwithin the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In an ultra high frequency system, a structure adapted for removeably positioningan electric discharge device having an envelope enclosing a plurality of electrodes, a base member sealed to said envelope including a plurality of terminal posts external to said envelope connected to said electrodes and an external orientation protuberance housing a concentric transmission line connected to one `of said electrodes, said structure comprising a wave guide of the hollow-pipe type. a socket having resilient contact means adapted to receive and removeably position said terminal posts, and a section of concentric transmission line inter-positioned between said wave guide and saidsocket including inner and outer conductors 'adapted resiliently to engage the corresponding members of said first mentioned transmission line, whereby upon insertion of said discharge device in said` `socket conductive connection is made between said lines, said second mentioned transmission line extending into said wave guide and serving as energizing electrode meansl ture adapted for removeably positioningan electric discharge device having an envelope enclosing a plurality of electrodes, a base member sealed to ksaid envelope including a plurality of terminal posts external to said envelope connected to said electrodes and an external orientation protuberance housing a concentric transmission line connected to one of said electrodes, said structure comprising a wave guide of the hollow-pipe type, a socket having resilient contact means adapted to receive and removeably position said terminal posts, and a section of concentric transmission line including inner and outer conductors adapted resiliently to engage the corresponding members of said first mentioned transmission line and nxedly positioned with respect to said socket whereby upon insertion of said discharge device in said socket conductive connection is made between said lines, said second mentioned transmission line extending into said wave guide andv serving as energizing electrode means therefor.

3. In an ultra high frequency system, a structure adapted for removeably positioning an electric discharge device having an envelope enclosing a plurality of electrodes, a base member sealed to said envelope including a pluralitywof terminal posts external to said envelope connected to said electrodes and an external orientation protuberance housing a concentric transmission iine connected to one of said electrodes. said structure comprising a wave guide of the hollow-pipe type, a socket having resilientcontact means adapted to receive and removeably position said terminal posts, a section of concentric transmission line including inner and outer conductors adapted resiliently to engage the corresponding members of said first mentioned transmission line and flxedly positioned with respect to said socket whereby upon insertion of said discharge device in said socket conductive connection is made between said lines, said second mentioned transmission line extending into said wave guide and serving as energizing electrode means therefor,` and a tunable section of transmission line constituting an extension of said first mentioned section for tuning said wave guide.

4. In an ultra high frequency system, a structure adapted for removeably positioning an electric discharge device having an envelope enclosing a plurality of electrodes, a base member sealed to said envelope including a plurality of `terminal posts external to said envelope concentric transmission line including inner vand outer conductors adapted resiliently to engage the corresponding members of said first mentioned transmission line and flxedly positioned with respect to said socket within said box whereby upon insertion of said discharge device in said socket conductive connection is made between said lines, said second mentioned transmission line extending into said wave guide and serving as energizing electrode means therefor.

- JAMES M. LAFFERTY.

REFERENCES `crlrzi) The following references are of record in the file of this patent:

UNITED STATES PATENTS 65 Number Name Date 2,129,713 Southworth Sept. 13. 1938 2,372,193 Fisk Mar. 27, 1945 2,375,223 Hansen et al. May 8, 1945 

